Substrate processing apparatus and processing liquid supply method

ABSTRACT

A substrate processing apparatus includes a processing liquid supply mechanism  70  configured to supply a SPM liquid to a substrate; a temperature adjusting unit (heater)  303  configured to adjust a temperature of the SPM liquid at a time when the SPM liquid is supplied to the substrate from the processing liquid supply mechanism  70;  an acquisition unit (temperature sensor)  80  configured to acquire temperature information of the SPM liquid on a surface of the substrate; and a control unit  18  configured to set an adjustment amount of the temperature adjusting unit (heater)  303  based on the temperature information of the SPM liquid acquired by the acquisition unit (temperature sensor)  80.  The temperature adjusting unit (heater)  303  adjusts, based on the adjustment amount set by the control unit  18,  the temperature of the SPM liquid at the time when the SPM liquid is supplied to the substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No.2016-189825 filed on Sep. 28, 2016, the entire disclosures of which areincorporated herein by reference.

TECHNICAL FIELD

The embodiments described herein pertain generally to a technique ofprocessing a substrate by supplying a heated processing liquid onto thesubstrate.

BACKGROUND

In a manufacturing process of a semiconductor device, a resist filmhaving a preset pattern is formed on a processing target film which isformed on a substrate such as a semiconductor wafer (hereinafter, simplyreferred to as “wafer”), and a processing such as etching or ionimplantation is performed on the processing target film by using thisresist film as a mask. After the processing is completed, the resistfilm which is no more necessary is removed from the wafer. A SPMprocessing is often performed to remove the resist film. This SPMprocessing is performed by supplying a high-temperature SPM (SulfuricAcid Hydrogen Peroxide Mixture) liquid prepared by mixing sulfuric acidand hydrogen peroxide onto the resist film.

Described in Patent Document 1 is a substrate processing apparatusconfigured to generate a SPM liquid of a required temperature byperforming a temperature adjustment of sulfuric acid through a heaterprovided in a sulfuric acid supply path and configured to supply thegenerated SPM liquid of the required temperature onto the substrate.Here, a relationship between a temperature of the sulfuric acid beforebeing mixed and a temperature of the SPM liquid discharged from a SPMnozzle is previously investigated through an experiment, and anoperational condition for the heater is determined based on thisrelationship.

Patent Document 1: Japanese Patent Laid-open Publication No. 2013-207080

If, however, processing conditions such as the rotation number of thesubstrate, a gas exhaust rate, a sulfuric acid concentration of theprocessing liquid, or the like are changed minutely, there is a concernthat the SPM liquid of the required temperature may not be supplied ontothe substrate with high accuracy just by using the operational conditionwhich is determined through the experiment.

SUMMARY

In view of the foregoing, exemplary embodiments provide a techniquecapable of performing a more accurate a processing with a SPM liquid ofa required temperature.

In one exemplary embodiment, there is provided a substrate processingapparatus. The substrate processing apparatus includes a processingliquid supply mechanism configured to generate a SPM liquid by mixingsulfuric acid and hydrogen peroxide and supply the generated SPM liquidto a substrate; a temperature adjusting unit configured to adjust atemperature of the SPM liquid at a time when the SPM liquid is suppliedto the substrate from the processing liquid supply mechanism; anacquisition unit configured to acquire temperature information of theSPM liquid on a surface of the substrate; and a control unit configuredto set an adjustment amount of the temperature adjusting unit based onthe temperature information acquired by the acquisition unit. Thetemperature adjusting unit adjusts, based on the adjustment amount setby the control unit, the temperature of the SPM liquid at the time whenthe SPM liquid is supplied to the substrate from the processing liquidsupply mechanism.

According to the exemplary embodiment, the processing with the SPMliquid of the required temperature can be performed more accurately.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

In the detailed description that follows, embodiments are described asillustrations only since various changes and modifications will becomeapparent to those skilled in the art from the following detaileddescription. The use of the same reference numbers in different figuresindicates similar or identical items.

FIG. 1 is a plan view illustrating an outline of a substrate processingsystem according to an exemplary embodiment;

FIG. 2 is a diagram illustrating an outline of a processing unitaccording to the exemplary embodiment;

FIG. 3 is a diagram illustrating a specific configuration example of aprocessing liquid supply system in the substrate processing systemaccording to a first exemplary embodiment;

FIG. 4 is a flowchart for describing details of a substrate processingperformed by the processing unit according to the present exemplaryembodiment;

FIG. 5A to FIG. 5C are diagrams showing an example of a temperaturedistribution of a SPM liquid on a wafer as temperature information;

FIG. 6 is a flowchart for describing a control over temperatureadjustment of the SPM liquid according to the first exemplaryembodiment;

FIG. 7 is a flowchart for describing a control over temperatureadjustment of the SPM liquid according to a second exemplary embodiment;

FIG. 8 is a diagram illustrating a specific configuration example of aprocessing liquid supply system in the substrate processing systemaccording to a third exemplary embodiment;

FIG. 9A and FIG. 9B are graphs showing time variations of a temperatureof the SPM liquid and a concentration of sulfuric acid in a storagetank; and

FIG. 10 is a flowchart for describing a control over temperatureadjustment of the SPM liquid according to the third exemplaryembodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part of the description. In thedrawings, similar symbols typically identify similar components, unlesscontext dictates otherwise. Furthermore, unless otherwise noted, thedescription of each successive drawing may reference features from oneor more of the previous drawings to provide clearer context and a moresubstantive explanation of the current exemplary embodiment. Still, theexemplary embodiments described in the detailed description, drawings,and claims are not meant to be limiting. Other embodiments may beutilized, and other changes may be made, without departing from thespirit or scope of the subject matter presented herein. It will bereadily understood that the aspects of the present disclosure, asgenerally described herein and illustrated in the drawings, may bearranged, substituted, combined, separated, and designed in a widevariety of different configurations, all of which are explicitlycontemplated herein.

Hereinafter, exemplary embodiments will be explained in detail withreference to the accompanying drawings, which form of a part of thedescription.

First Exemplary Embodiment

FIG. 1 is a plan view illustrating an outline of a substrate processingsystem provided with a processing unit according to an exemplaryembodiment of the present disclosure. In the following, in order toclarify positional relationships, the X-axis, Y-axis and Z-axis whichare orthogonal to each other will be defined. The positive Z-axisdirection will be regarded as a vertically upward direction.

As illustrated in FIG. 1, a substrate processing system 1 includes acarry-in/out station 2 and a processing station 3. The carry-in/outstation 2 and the processing station 3 are provided adjacent to eachother.

The carry-in/out station 2 is provided with a carrier placing section 11and a transfer section 12. In the carrier placing section 11, aplurality of carriers C is placed to accommodate a plurality of wafers(substrates) horizontally.

The transfer section 12 is provided adjacent to the carrier placingsection 11, and provided with a substrate transfer device 13 and adelivery unit 14. The substrate transfer device 13 is provided with asubstrate holding mechanism configured to hold the wafer W. Further, thesubstrate transfer device 13 is movable horizontally and vertically andpivotable around a vertical axis, and transfers the wafers W between thecarriers C and the delivery unit 14 by using the substrate holdingmechanism.

The processing station 3 is provided adjacent to the transfer section12. The processing station 3 is provided with a transfer section 15 anda plurality of processing units 16. The plurality of processing units 16is arranged at both sides of the transfer section 15.

The transfer section 15 is provided with a substrate transfer device 17therein. The substrate transfer device 17 is provided with a substrateholding mechanism configured to hold the wafer W. Further, the substratetransfer device 17 is movable horizontally and vertically and pivotablearound a vertical axis. The substrate transfer device 17 transfers thewafers W between the delivery unit 14 and the processing units 16 byusing the substrate holding mechanism.

The processing units 16 perform a predetermined substrate processing onthe wafers W transferred by the substrate transfer device 17.

Further, the substrate processing system 1 is provided with a controldevice 4. The control device 4 is, for example, a computer, and includesa control unit 18 and a storage unit 19. The storage unit 19 stores aprogram that controls various processings performed in the substrateprocessing system 1. The control unit 18 controls the operations of thesubstrate processing system 1 by reading and executing the programstored in the storage unit 19.

Further, the program may be recorded in a computer-readable recordingmedium, and installed from the recording medium to the storage unit 19of the control device 4. The computer-readable recording medium may be,for example, a hard disc (HD), a flexible disc (FD), a compact disc(CD), a magnet optical disc (MO), or a memory card.

In the substrate processing system 1 configured as described above, thesubstrate transfer device 13 of the carry-in/out station 2 first takesout a wafer W from a carrier C placed in the carrier placing section 11,and then places the taken wafer W on the delivery unit 14. The wafer Wplaced on the delivery unit 14 is taken out from the delivery unit 14 bythe substrate transfer device 17 of the processing station 3 and carriedinto a processing unit 16.

The wafer W carried into the processing unit 16 is processed by theprocessing unit 16, and then, carried out from the processing unit 16and placed on the delivery unit 14 by the substrate transfer device 17.After the processing of placing the wafer W on the delivery unit 14, thewafer W returns to the carrier C of the carrier placing section 11 bythe substrate transfer device 13.

Now, a schematic configuration of the processing unit 16 will beexplained with reference to FIG. 2. FIG. 2 is a diagram illustrating anoutline of the processing unit 16. The processing unit 16 according tothe present exemplary embodiment is configured to supply a SPM (SulfuricAcid Hydrogen Peroxide Mixture), which is a mixed solution of sulfuricacid and hydrogen peroxide, onto the wafer W. As illustrated in FIG. 2,the processing unit 16 is provided with a chamber 20, a substrateholding mechanism 30, a nozzle 40, and a recovery cup 50.

The chamber 20 accommodates the substrate holding mechanism 30, thenozzle 40, and the recovery cup 50. A fan filter unit (FFU) 21 isprovided on the ceiling of the chamber 20. The FFU 21 forms a downflowin the chamber 20.

The substrate holding mechanism 30 is provided with a holding unit 31, asupporting member 32, and a driving unit 33. The holding unit 31 isconfigured to hold the wafer W horizontally. The supporting member 32 isa vertically extended member, and has a base end portion supportedrotatably by the driving unit 33 and a tip end portion supporting theholding unit 31 horizontally. The driving unit 33 is configured torotate the supporting member 32 around the vertical axis. In thesubstrate holding mechanism 30, the supporting member 32 is rotated byusing the driving unit 33, so that the holding unit 31 supported by thesupporting member 32 is rotated, and, hence, the wafer W held by theholding unit 31 is rotated.

The nozzle 40 is configured to supply the SPM liquid onto the wafer W.The nozzle 40 is connected to a processing liquid supply mechanism 70.

The recovery cup 50 is disposed to surround the holding unit 31, andconfigured to collect the SPM liquid scattered from the wafer W causedby the rotation of the holding unit 31. A drain port 51 is formed in thebottom of the recovery cup 50, and the SPM liquid collected by therecovery cup 50 is drained from the drain port 51 to the outside of theprocessing unit 16. Further, an exhaust port 52 is formed in the bottomof the recovery cup 50 to exhaust a gas supplied from the FFU 21 to theoutside of the processing unit 16.

Now, a specific configuration example of a processing liquid supplysystem in the substrate processing system 1 according to a firstexemplary embodiment will be discussed with reference to FIG. 3. FIG. 3is a diagram illustrating a specific configuration example of theprocessing liquid supply system in the substrate processing system 1according to the first exemplary embodiment.

The processing liquid supply mechanism 70 is equipped with a sulfuricacid supply source 301, a sulfuric acid supply path (a first path) 302,a heater 303 as a temperature adjusting unit, and a valve 304, as asulfuric acid supply system. The sulfuric acid supply source 301 isconfigured to supply sulfuric acid of an ordinary temperature (a roomtemperature). As the valve 304 is driven into an open state from aclosed state, the sulfuric acid from the sulfuric acid supply source 301flows through the sulfuric acid supply path 302, and the heater 303heats the sulfuric acid flowing through the sulfuric acid supply path302.

In the present exemplary embodiment, an initial setting of a targettemperature of the sulfuric acid is 90° C. Since the temperature of thesulfuric acid supplied from the sulfuric acid supply source 301 is about25° C., the heater 303 only having a heating function is used as thetemperature adjusting unit. In case of, however, supplying sulfuric acidpreviously maintained at a high temperature, the temperature of theliquid may need to be reduced to the target temperature. Thus, Coolnicsor the like having a cooling function may be used as the temperatureadjusting unit.

The processing liquid supply mechanism 70 is also equipped with ahydrogen peroxide supply source 305, a hydrogen peroxide supply path(second path) 306 and a valve 307, as a hydrogen peroxide supply system.The hydrogen peroxide supply source 305 is configured to supply hydrogenperoxide of an ordinary temperature (a room temperature). As the valve307 is driven into an open state from a closed state, the hydrogenperoxide from the hydrogen peroxide supply source 305 flows through thehydrogen peroxide supply path 306.

The processing liquid supply mechanism 70 further includes a mixing unit308. The mixing unit 308 is configured to mix therein the sulfuric acidsupplied from the sulfuric acid supply path 302 and the hydrogenperoxide supplied from the hydrogen peroxide supply path 306 at a presetmixing ratio to generate the SPM liquid as the mixed solution. Thegenerated SPM liquid is supplied into the processing unit 16 anddischarged from the nozzle 40 (an example of a discharging unit).

The mixing unit 308 has a function of varying the mixing ratio inresponse to an instruction from the control unit 18. In the presentexemplary embodiment, an initial setting of the mixing ratio is sulfuricacid: hydrogen peroxide=2:1.

Now, the details of a substrate processing performed by the processingunit 16 according to the present exemplary embodiment will be discussedwith reference to FIG. 4. FIG. 4 is a flowchart for describing anexample of sequences of the substrate processing performed by theprocessing unit 16 according to the first exemplary embodiment. Eachprocessing sequence shown in FIG. 4 is performed under the control ofthe control unit 18.

First, in the processing unit 16, a carry-in processing of a wafer W isperformed (process S101). To elaborate, the wafer W is carried into thechamber 20 (see FIG. 2) of the processing unit 16 by the substratetransfer device 17 (see FIG. 1) and held by the holding unit 31. Then,the processing unit 16 rotates the holding unit 31 at a presetrotational speed (e.g., 50 rpm).

Subsequently, in the processing unit 16, a SPM supply processing isperformed (process S102). In the SPM supply processing, as the valve 304and the valve 307 are opened for a preset time period (e.g., 30seconds), the SPM is supplied onto a top surface of the wafer W from thenozzle 40. The SPM supplied onto the wafer W is diffused on the surfaceof the wafer W by a centrifugal force generated by the rotation of thewafer W.

In this SPM supply processing, a resist formed on the top surface of thewafer W, for example, is removed by using a strong oxidizing power ofCaro's acid contained in the SPM and heat of reaction between thesulfuric acid and the hydrogen peroxide.

Further, flow rates of the sulfuric acid and the hydrogen peroxide aredetermined based on the mixing ratio of the sulfuric acid and thehydrogen peroxide. Since a proportion of the sulfuric acid in the SPM ishigher than that of the hydrogen peroxide, the flow rate of the sulfuricacid is set to be higher than the flow rate of the hydrogen peroxide.

Upon the completion of the SPM supply processing in the process S102, arinsing processing is performed in the processing unit 16 (processS103). In this rinsing processing, a rinse liquid (e.g., DIW) issupplied onto the top surface of the wafer W from a non-illustratedrinse liquid supply unit. The DIW supplied onto the wafer W is diffusedon the surface of the wafer W by a centrifugal force generated by therotation of the wafer W. As a result, the SPM remaining on the wafer Wis washed away by the DIW.

Thereafter, a drying processing is performed in the processing unit 16(process S104). In this drying processing, the wafer W is rotated at apreset rotational speed (e.g., 1000 rpm) for a predetermined timeperiod. As a result, the DIW remaining on the wafer W is scattered away,so that the wafer W is dried. Then, the rotation of the wafer W isstopped.

Then, a carry-out processing is performed in the processing unit 16(process S105). In the carry-out processing, the wafer W held by theholding unit 31 is transferred onto the substrate transfer device 17.Upon the completion of the carry-out processing, the substrateprocessing on the single sheet of wafer W is completed.

Now, acquisition of temperature information of the SPM liquid on thewafer W using a temperature sensor 80 (acquisition unit) will beexplained. The temperature sensor 80 is configured to irradiate aninfrared ray as irradiation light and receive reflection light from thesurface of the wafer W. In the reflection light received by thetemperature sensor 80, a component reflected by the SPM liquid on thewafer W is dominant, and, here, an intensity value of the reflectionlight is regarded as information of the SPM liquid.

The temperature senor 80 is configured to convert the intensity value ofthe received reflection light to a temperature value, and acquires atemperature distribution regarding a plane region including the wafer Was temperature information. In the present exemplary embodiment, aresolution of the temperature distribution acquired by the temperaturesensor 80 is 10 mm×10 mm. The acquired temperature information is sentto the control unit 18 continually at a preset time interval (e.g., 1sec). The control unit 18 receives the temperature information sent fromthe temperature sensor 80 and stores the received temperatureinformation in the storage unit 19.

FIG. 5A to FIG. 5C are diagrams for describing the temperatureinformation of the SPM liquid used for the control unit 18 to perform atemperature adjustment processing to be described later. In the presentexemplary embodiment, the control unit 18 simplifies the temperatureinformation acquired from the temperature sensor 80 into 21 zones toeasily perform calculation of a difference value to be described later.To elaborate, a single central zone, eight intermediate zones and twelveperipheral zones are defined corresponding to positions on the wafer W.In FIG. 5A, the central zone is marked by “C”; the intermediate zones,“M”; and the peripheral zones, “E”. Each zone has a size of 60 mm×60 mmand corresponds to 36 temperature values stored by being received fromthe temperature sensor 80. Each of the 36 temperature values correspondsto the temperature value of every single region of 10 mm×10 mm. Thecontrol unit 18 calculates an average value of the 36 temperature valuesfor each zone and obtains a single temperature value for thecorresponding zone.

FIG. 5B is a diagram showing a temperature distribution characteristicof the SPM liquid on the surface of the wafer W in case of fixing asupply position from the nozzle 40 to a center of the wafer W (a centerof the central zone C).

The temperature of the SPM liquid tends to be highest (158° C.) at thecentral zone C to which the supplied SPM liquid is landed and tends tobe decreased as it goes toward the intermediate zones M and theperipheral zones E. It is deemed to be because a peripheral portion ofthe wafer W is easily cooled by ambient air around the wafer W due to ahigh circumferential velocity of the wafer W at the peripheral portionof the wafer, because a processing region of the SPM liquid per a unitvolume is large, and because the SPM liquid is degraded as it reactswith the resist or the heat of the SPM liquid is lost to the wafer Wwhile the SPM liquid is diffused to the peripheral portion by acentrifugal force.

When such a temperature distribution characteristic appears, if thetemperature of the SPM liquid is adjusted to be optimized for thecentral zone C, the resist may not be sufficiently removed from theperipheral zones E for a set processing time. Thus, it may be desirableto perform the temperature adjustment with reference to a zone havingthe lowest temperature among the peripheral zones E. To elaborate, amongthe peripheral zones E in FIG. 5B, there is a zone having a temperatureof 151° C., which is the lowest, and it has a difference of 9° C. from arequired temperature (160° C.) of the SPM liquid. Accordingly, thecontrol unit 18 changes a target value of the temperature adjustment ofthe sulfuric acid from 90° C. to a value equal to or higher than 99° C.

Here, a Caro's acid concentration in the SPM liquid and a reactiontemperature will be explained. First, the Caro's acid concentration willbe discussed. Caro's acid (H₂SO₅) is generated according to a reactionformula of ‘H₂SO₄+H₂O₂→H₂SO₅+H₂O . . . (Expression 1).’ If the Caro'sacid concentration in the SPM liquid increases, a resist film peelingperformance of the SPM liquid is improved. Even if the Caro's acidconcentration is increased, damage on the wafer W is not increased a lot(as compared to cases when the temperature of the SPM liquid isincreased and when a moisture amount of the SPM liquid is increased).Thus, it may be desirable to supply the SPM liquid to the wafer W in thestate that the Caro's acid concentration is increased as high aspossible. The Caro's acid concentration increases with a lapse of timeafter the sulfuric acid and the hydrogen peroxide are mixed anddecreases as the Caro's acid is decomposed after the Caro's acidconcentration reaches a peak value.

In designing the apparatus, a distance between the nozzle 40 and themixing unit 308 may be optimized such that the SPM liquid is dischargedto the wafer W in the state that the Caro's acid concentration is closeto the peak value (maximum value) when the mixing ratio in the mixingunit 308 and the temperature of the sulfuric acid before being mixed areregulated to be constant and flow velocities of the sulfuric acid andthe hydrogen peroxide are set to be constant as well.

Meanwhile, the temperature of the SPM liquid shows the same tendency asthe variation of the Caro's acid concentration. That is, after thesulfuric acid and the hydrogen peroxide are mixed, the temperature ofthe SPM liquid increases with a lapse of time and decreases gradually asheat is dissipated through a wall surface of the supply path after thetemperature of the SPM liquid reaches a peak value. Here, however, itshould be noted that a time period taken to reach the peak value of theCaro's acid concentration and a time period taken to reach the peakvalue of the SPM temperature may not be same.

In the temperature distribution characteristic of FIG. 5B according tothe present exemplary embodiment, the distance between the nozzle 40 andthe mixing unit 308 is optimized such that the SPM liquid is dischargedin the state that the temperature of the SPM liquid is close to the peakvalue (maximum value). As a result, as the heat of reaction is weakenedgradually after the SPM liquid is discharged and the liquid is diffusedtoward the peripheral zones E, the temperature of the SPM liquid isdecreased gradually.

In the example of FIG. 5B, since the central zone C is a region by whichthe entire SPM liquid passes immediately after being landed to the waferW and where the circumferential velocity of the wafer W is minimum, thetemperature information having the highest reliability can be obtained.Accordingly, if it is possible to estimate a temperature decrementtoward the periphery of the wafer W, the control unit 18 may decide thetarget value of the temperature adjustment of the sulfuric acid based onthe temperature value of the central zone C. By way of example, if thetemperature value of the central zone C is 158° C. and the estimatedtemperature decrement at the peripheral zones E is 8° C., the targetvalue of the temperature adjustment becomes 90° C.+(160° C.−(158° C.−8°C.))=100° C.

FIG. 5C is a diagram showing the temperature distribution characteristicof the SPM liquid on the surface of the wafer W in case of moving thesupply position of the SPM liquid from the nozzle 40 repeatedly betweenthe center of the wafer W and the periphery thereof.

In the present exemplary embodiment, a cycle of the reciprocating of thenozzle 40 is set to be 2 seconds (from the center to the periphery: 1sec and from the periphery to the center: 1 sec). In FIG. 5C, there isobserved no big difference among the central zone C, the intermediatezones M and the peripheral zones E. It is because the SPM liquids havingvarious elapsed times according to the change of the position of thenozzle 40 are mixed on the wafer W.

Accordingly, in FIG. 5C, as an example method, an average value of thetemperature values of all of the 21 zones may be obtained, and thetemperature adjustment may be performed based on the obtained averagevalue. To elaborate, since the average value is calculated to be 158° C.in FIG. 5C, there is a difference of 2° C. from the required temperatureof the SPM liquid. Thus, the control unit 18 may change the target valueof the temperature adjustment of the sulfuric acid from 90° C. to avalue of 92° C. or higher. As another method, the lowest temperaturevalue may be specified from all the 21 zones, and the temperatureadjustment may be performed based on this lowest temperature value. Toelaborate, in FIG. 5C, since the lowest temperature value is 156° C.,there is a difference of 4° C. from the required temperature of the SPMliquid. In this case, the control unit 18 may change the target value ofthe temperature adjustment of the sulfuric acid from 90° C. to a valueof 94° C. or higher.

Furthermore, if there still exists a tendency that the temperaturedeclines toward the outer regions nevertheless of the reciprocatingmovement of the nozzle 40, a temperature of a zone having the lowesttemperature of the SPM liquid among the peripheral zones E and theaverage value of the temperatures of all the zones may beweight-averaged with a preset weighting (e.g., 2:1) and a differencebetween the obtained weight-average value and the required temperatureof the SPM liquid may be specified as the difference value. Furthermore,the exemplary embodiment is not limited to the mentioned examples, and avalue obtained by providing a preset weighting to the temperature valuedescribed with reference to FIG. 5B or FIG. 5C may be used for thecalculation.

A control over the temperature adjustment of the SPM liquid, which isperformed by the control unit 18 according to the exemplary embodiment,will be explained with reference to a flowchart of FIG. 6.

First, in the state that the liquid film of the SPM liquid is formed onthe surface of the wafer W as the SPM supply processing in the processS102 of the flowchart of FIG. 4 is begun, the control unit 18 calculatesthe temperature distribution characteristic of the SPM liquid shown inFIG. 5A to FIG. 5C based on the temperature information acquired by thetemperature sensor 80 (process S201).

Then, the difference value from the required temperature of the SPMliquid is specified (process S202). As stated above with reference toFIG. 5A to FIG. 5C, in the present exemplary embodiment, the differencevalue can be obtained by using at least one of the temperature value ofthe central zone C of the wafer W, the temperature values of theperipheral zones E, the average temperature value of all the zones andthe lowest temperature value among all the zones. One of these methodsmay be selected based on the structures of the processing unit 16 andthe processing liquid supply mechanism 70 (the length of the liquidpath, etc.), the details of setting of the recipe for the SPMprocessing, and so forth.

Subsequently, the control unit 18 changes the set temperature of theheater 303 based on the difference value obtained in the process S202(process S203). As stated above, a next target value needs to be changedto equal to or higher than a value obtained by adding the differencevalue to the current target value. Here, the changed level may be set toan optimum amount based on an interval time of a feedback control to bedescribed later, performance of the heater 303, and so forth.

Thereafter, the control unit 18 determines whether a preset intervaltime has elapsed from a time when the temperature setting of the processS203 is performed (process S204).

As described above, since a preset time is required before the sulfuricacid heated by the heater 303 is discharged from the nozzle 40 afterbeing mixed in the mixing unit 308, a preset time period needs to passby after the change is made to the temperature setting until theoperation of the feedback control can be checked. For example, assumingthat a time taken for the SPM liquid to reach the nozzle 40 from theheater 303 is 1 sec and a time taken for the discharged SPM liquid toreach the periphery from a center of the wafer is 1 sec, the intervaltime is set to be of a value equal to or larger than 2 sec, for example,5 sec.

If it is found out that the interval time has elapsed (process S204,Yes), it is determined whether a set processing time of the SPMprocessing set in the recipe has elapsed (process S205). If it isdetermined that the set processing time has not passed by (process S205,No), the processings from the process S201 are repeated by using thetemperature information of the SPM liquid on the wafer W acquired by thetemperature sensor 80.

Meanwhile, if it is determined that the set processing time has elapsed(process S205, Yes), the temperature adjustment is ended, and asubsequent rinsing processing is performed.

In the present exemplary embodiment, the temperature information of theSPM liquid on the surface of the wafer W is obtained by the temperaturesensor 80, and, based on this acquired temperature information of theSPM liquid, the control unit 18 sets the heating amount in the heater303 which heats the sulfuric acid. Accordingly, the processing with theSPM liquid of the required temperature can be performed accurately.

Further, in the present exemplary embodiment, since the sulfuric acidflowing in the sulfuric acid supply path 302 before being mixed in themixing unit 308 is heated by the heater 303, a heater for heating theSPM liquid after being mixed in the mixing unit 308 need not be providedwithin the processing unit 16, so that the complication of the apparatuscan be avoided.

Furthermore, in the present exemplary embodiment, since the feedbackcontrol is performed in a unit of the interval time shorter than the setprocessing time of the processing with the SPM liquid, the temperatureadjustment of the SPM liquid can be performed based on the temperatureinformation on the wafer W in a real time.

Moreover, in the present exemplary embodiment, the difference valuebetween the required temperature of the SPM liquid and the temperatureof the SPM liquid on the wafer W is calculated based on the temperaturedistribution characteristic calculated from the temperature informationacquired by the temperature sensor 80, and the target temperature of theheater 303 is determined based on the calculated difference value.Accordingly, the temperature adjustment can be performed by flexiblyspecifying the target temperature depending on the structure of theapparatus and the details of the recipe of the processing, and thetemperature value of the central zone C of the SPM liquid on the waferW, the temperature values of the peripheral zones E thereof, the averagevalue of all the zones, the lowest value among all the zones or thelike.

Second Exemplary Embodiment

The first exemplary embodiment has been described for the example wherethe heater 303 is used as the temperature adjusting unit. However, thetemperature adjusting unit is not merely limited to having a heating orcooling function. In this second exemplary embodiment, an example ofusing the mixing unit 308 as the temperature adjusting unit will bedescribed.

To be specific, the reaction temperature is increased by increasing aratio of the hydrogen peroxide with respect to the sulfuric acid. In thepresent exemplary embodiment, the hydrogen peroxide is heated to theordinary temperature (a room temperature) and the sulfuric acid isheated to 90° C. Thus, if the mixing ratio of the sulfuric acid isreduced, the temperature of the SPM liquid at the time when it is mixedmay be rather decreased than before. After that, however, an incrementof the heat of reaction between the hydrogen peroxide and the sulfuricacid may become dominant in the temperature adjustment.

A control over the temperature adjustment of the SPM liquid performed bythe control unit 18 according to the present exemplary embodiment willbe explained with reference to a flowchart of FIG. 7. In FIG. 7,processes except a process S303 are the same as the processes S201 toS205 in FIG. 6, respectively, and, thus, redundant description will beomitted here.

In the process S303, the control unit 18 changes a mixing ratio in themixing unit 308 based on the difference value obtained in a process S302(process S303).

Assume that an initial mixing ratio in the mixing unit 308 is 2:1 andthe difference value obtained in the process S302 is 5° C. (lower). Inthis case, the control unit 18 changes the mixing ratio in the mixingunit 308 to a value of, e.g., 3:2 which allows estimation of thetemperature rise of 5° C.

In the present exemplary embodiment, through previous experiments,temperature values of the SPM liquid on the wafer W (e.g., the centralzone C) when varying only the mixing ratio while maintaining the otherconditions same are measured, and a relationship between the mixingratio and the temperature of the SPM liquid on the wafer W is calculatedand stored in the storage unit 19. Accordingly, the control unit 18 mayset the degree of variation of the mixing ratio based on thistemperature relationship.

In the present exemplary embodiment, the same effect as obtained in thefirst exemplary embodiment can be achieved. Further, in case ofperforming the temperature adjustment by using the mixing unit 308, anactual temperature change is faster than in case of using the heater 303or the like. Thus, the interval time in the feedback control can be setto be relatively shorter, and precise temperature adjustment with highresponsiveness can be achieved.

Third Exemplary Embodiment

Now, a specific configuration example of a processing liquid supplysystem in the substrate processing system 1 according to a thirdexemplary embodiment will be discussed with reference to FIG. 8. FIG. 8is a diagram illustrating the specific configuration example of theprocessing liquid supply system in the substrate processing system 1according to the third exemplary embodiment.

As depicted in FIG. 8, a processing liquid supply mechanism 70 isequipped with, as a sulfuric acid supply system, a storage tank 102configured to store the sulfuric acid; a circulation path 104 extendedfrom the storage tank 102 and returned to the storage tank 102; and amultiple number of branch paths 112 branched off from the circulationpath 104 and connected to the respective processing units 16.

The storage tank 102 is provided with a liquid surface sensor S1. Forexample, the liquid surface sensor S1 is provided at a lateral side ofthe storage tank 102, and is configured to detect a liquid surface ofthe sulfuric acid which is stored in the storage tank 102. To bespecific, the liquid surface sensor S1 is configured to detect thelowest liquid surface within the storage tank 102. The detection resultby the liquid surface sensor S1 is output to the control unit 18.

The circulation path 104 is provided with a pump 106, a filter 108, aheater 109 and a concentration meter 110 in sequence from the upstreamside thereof. The pump 106 is configured to generate a circulation flowcoming out from the storage tank 102 and returning back to the storagetank 102 after passing through the circulation path 104. The filter 108is configured to remove a contaminant such as a particle contained inthe sulfuric acid. The heater 109 is controlled by the control unit 18to heat the sulfuric acid circulating in the circulation path 104 to aset temperature. The concentration meter 110 is configured to detect aconcentration of the sulfuric acid circulating in the circulation path104 and is configured to send the detection result to the control unit18.

The multiple number of branch paths 112 are connected to portions of thecirculation path 104 downstream of the concentration meter 110. Eachbranch path 112 is connected to a mixing unit 45 of the correspondingprocessing unit 16 to be described later and serves to supply thesulfuric acid flowing in the circulation path 104 to the correspondingmixing unit 45. Each branch path 112 is provided with a valve 113.

Furthermore, the processing liquid supply mechanism 70 is equipped witha hydrogen peroxide supply path 160, a valve 161 and a hydrogen peroxidesupply source 162 as a hydrogen peroxide supply system. One end of thehydrogen peroxide supply path 160 is connected to the hydrogen peroxidesupply source 162 via the valve 161, and the other end thereof isconnected to the mixing unit 45 of the processing unit 16 to bedescribed later. The processing liquid supply mechanism 70 is configuredto supply the hydrogen peroxide from the hydrogen peroxide supply source162 into the mixing unit 45 of the processing unit 16 through thehydrogen peroxide supply path 160.

In addition, the processing liquid supply mechanism 70 is furtherequipped with a supply path 170, a valve 171 and a sulfuric acid supplysource 172. One end of the supply path 170 is connected to the sulfuricacid supply source 172 via the valve 171, and the other end thereof isconnected to the storage tank 102. The sulfuric acid supply source 172supplies the sulfuric acid. The processing liquid supply mechanism 70 isconfigured to supply the sulfuric acid from the sulfuric acid supplysource 172 to the storage tank 102 through the supply path 170.

Further, though not illustrated here, the processing liquid supplymechanism 70 has a rinse liquid supply path for supplying the rinseliquid into the processing unit 16. The rinse liquid may be, forexample, but not limitation, DIW (pure water).

The processing liquid supply mechanism 70 includes the mixing unit 45.The mixing unit 45 is configured to generate the SPM liquid as a mixedsolution by mixing the sulfuric acid supplied from the branch path 112and the hydrogen peroxide supplied from the hydrogen peroxide supplypath 160. The mixing unit 45 supplies the generated SPM liquid to thenozzle 40 (see FIG. 2).

Moreover, the drain port 51 of each processing unit 16 is connected to adrain path 54 via a branch path 53. The SPM liquid used in eachprocessing unit 16 is drained into the drain path 54 from the drain port51 via the branch path 53.

In the present exemplary embodiment, the supply of the SPM liquid andthe supply of the rinse liquid are performed by using the single nozzle40. However, the processing unit 16 may be further equipped with anozzle for supplying the rinse liquid.

The substrate processing system 1 further includes a switching unit 90,a recovery path 114, and a waste path 115. The switching unit 90 isconnected to the drain path 54, the recovery path 114 and the waste path115 and is configured to switch a target destination of the SPM liquidflowing in the drain path 54 after being used between the recovery path114 and the waste path 115 under the control of the control unit 18.

One end of the recovery path 114 is connected to the switching unit 90,and the other end thereof is connected to a recovery tank 116. Therecovery path 114 is provided with the recovery tank 116, a pump 117 anda filter 118 in sequence from the upstream side thereof. The recoverytank 116 is configured to temporarily store therein the SPM liquid whichhas been already used. The pump 117 is configured to generate a flowallowing the used SPM liquid stored in the recovery tank 116 to be sentto the recovery tank 102. The filter 118 is configured to remove acontaminant such as a particle contained in the used SPM liquid.

The waste path 115 is connected to the switching unit 90, and isconfigured to drain the used SPM liquid, which is flown into the wastepath 115 from the drain path 54 via the switching unit 90, to theoutside of the substrate processing system 1.

In the substrate processing system 1 according to the present exemplaryembodiment, there is performed a circulation temperature adjustmentprocessing of controlling the temperature of the sulfuric acidcirculating in the circulation path 104 by controlling the heater 109such that the temperature of the SPM liquid on the wafer W is maintainedconstant.

FIG. 9A is a graph showing a time variation of a temperature of the SPMliquid and a time variation of a concentration of the sulfuric acidwithin the storage tank 102 when the circulation temperature adjustmentprocessing is not performed. Further, FIG. 9B is a graph showing thetime variation of the temperature of the SPM liquid and the timevariation of the concentration of the sulfuric acid within the storagetank 102 when the circulation temperature adjustment processing isperformed.

As depicted in FIG. 9A, if the heater 109 is controlled such that thetemperature (circulation temperature) of the sulfuric acid circulatingin the circulation path 104 becomes constant, the temperature of the SPMliquid is reduced as much as a decrement of the heat of reaction betweenthe sulfuric acid and the hydrogen peroxide which is caused by adecrease of the concentration of the sulfuric acid within the storagetank 102.

In this regard, the control unit 18 controls the heater 109 such thatthe temperature of the SPM liquid becomes constant, as shown in FIG. 9B.That is, the control unit 18 controls the heater 109 such that thecirculation temperature increases as the concentration of the sulfuricacid within the storage tank 102 decreases. As a consequence,degradation of the performance of the SPM processing that might becaused by the decrease of the concentration of the sulfuric acid can besuppressed.

To implement the control method of FIG. 9B, the relationship between thelapse of time and the SPM temperature shown in FIG. 9A may beinvestigated by an experiment and stored previously, and thisrelationship may be used to set a temperature of the heating processing.This temperature information, however, may be different from temperatureinformation of the SPM liquid at the time when the SPM liquid isactually supplied to the wafer W.

In the present exemplary embodiment, the control unit 18 acquires thetemperature information from the temperature sensor 80 configured tomeasure the temperature of the SPM liquid on the wafer W, and sets thetarget temperature of the heater 109 based on the acquired temperatureinformation. Here, there exists the plurality of processing units 16. Inthe present exemplary embodiment, the target temperature of the heater109 is set based on the temperature information acquired from all theprocessing units 16.

A control over the temperature adjustment of the SPM liquid performed bythe control unit 18 according to the present exemplary embodiment willbe discussed with reference to a flowchart of FIG. 10.

The control in this flowchart is started when the SPM processing upon afirst wafer W is begun in the processing unit 16 after the wafers W areconsecutively transferred into the plurality of processing units 16 fromthe carrier C which is placed in the carrier placing section 11 whileaccommodating 25 sheets of wafers W therein.

In FIG. 10, processes S401 and S402 are the same as the processes S201and S202 in the first exemplary embodiment. However, in the processS401, temperature information is acquired only from, among all theprocessing units 16, a multiplicity of processing units 16 in which theSPM processing is performed. In the process S402, the lowest value amongthe difference values calculated for the multiplicity of processingunits 16 in which the SPM processing is performed is specified as arepresentative difference value. By defining the lowest value as therepresentative difference value, after the temperature adjustment, aprocessing with the SPM liquid of a temperature equal to or higher thanthe required temperature can be performed in all of the processingunits.

Thereafter, the target temperature of the heater 109 is determined byusing the representative difference value specified in the process S402(process S403). Here, since the method of determining the targettemperature is the same as described in the method of the firstexemplary embodiment, description thereof will be omitted here.

A process S404 is the same as the process S204 of the first exemplaryembodiment. In the present exemplary embodiment, the heater 109 as thetemperature adjusting unit is provided at the circulation path 104. As aresult, a length of the path led to the nozzle 40 is longer than that inthe first exemplary embodiment, so that it may be desirable that theinterval time is set to be comparatively longer. Furthermore, since theSPM processing is performed in the multiplicity of processing units 16at the same time, the interval time may be decided without depending onan individual set processing time or timing.

In a process S405, if the SPM processing upon the preset number (here,25 sheets) of wafers W accommodated in the carrier C is completed(process S405, Yes), the control over the temperature adjustment isfinished.

As stated above, in the third exemplary embodiment, based on thetemperature information acquired by the temperature sensor 80, thecontrol unit 18 sets the temperature to which the heater 109 heats thesulfuric acid circulating in the circulation path 104.

Accordingly, the same effect as that of the first exemplary embodimentcan be achieved. Further, as stated in the first and second exemplaryembodiments, since the units need not be controlled individually, thetemperature adjustment can be performed en bloc without complicating thecontrol mechanism. Further, since the SPM liquid of the same temperatureis supplied into all the units, the temperature of the recovered SPMliquid can be estimated, which allows the temperature management forrecycling to be easily performed.

In the third exemplary embodiment, the temperature information areacquired from the wafers W as the actual targets of the processing inthe processing units 16. However, the exemplary embodiment is notlimited thereto. By way of example, one of the processing units 16 maybe defined as one for a dummy wafer, and the SPM liquid may be suppliedonto the dummy wafer different from the wafers W accommodated in thecarrier C and the temperature information may be acquired from only thetemperature sensor 80 of this unit. Accordingly, the temperaturedistribution characteristic can be obtained regardless of the processingtiming of each wafer W taken out of the carrier C, so that the accuracyof the temperature adjustment can be improved.

The various exemplary embodiments have been described so far. Thetemperature adjusting units of the first and second exemplaryembodiments may be additionally provided in the circulation systemdescribed in the third exemplary embodiment. Further, the first to thirdexemplary embodiments are not limiting, and the present disclosure maybe applicable to another system.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting. The scope of the inventive concept is defined by thefollowing claims and their equivalents rather than by the detaileddescription of the exemplary embodiments. It shall be understood thatall modifications and embodiments conceived from the meaning and scopeof the claims and their equivalents are included in the scope of theinventive concept.

We claim:
 1. A substrate processing apparatus, comprising: a processingliquid supply mechanism configured to generate a SPM liquid by mixingsulfuric acid and hydrogen peroxide and supply the generated SPM liquidto a substrate; a temperature adjusting unit configured to adjust atemperature of the SPM liquid at a time when the SPM liquid is suppliedto the substrate from the processing liquid supply mechanism; anacquisition unit configured to acquire temperature information of theSPM liquid on a surface of the substrate; and a control unit configuredto set an adjustment amount of the temperature adjusting unit based onthe temperature information acquired by the acquisition unit, whereinthe temperature adjusting unit adjusts, based on the adjustment amountset by the control unit, the temperature of the SPM liquid at the timewhen the SPM liquid is supplied to the substrate from the processingliquid supply mechanism.
 2. The substrate processing apparatus of claim1, wherein the processing liquid supply mechanism comprises: a firstpath through which the sulfuric acid is flown; a second path throughwhich the hydrogen peroxide is flown; a mixing unit configured togenerate the SPM liquid by mixing the sulfuric acid from the first pathand the hydrogen peroxide from the second path at a preset mixing ratio;and a discharging unit configured to discharge the SPM liquid generatedby the mixing unit toward the substrate, wherein the temperatureadjusting unit is provided at the first path to adjust a temperature ofthe sulfuric acid flowing in the first path.
 3. The substrate processingapparatus of claim 1, wherein the processing liquid supply mechanismcomprises: a first path through which the sulfuric acid is flown; asecond path through which the hydrogen peroxide is flown; a mixing unitconfigured to generate the SPM liquid by mixing the sulfuric acid fromthe first path and the hydrogen peroxide from the second path at apreset mixing ratio; and a discharging unit configured to discharge theSPM liquid generated by the mixing unit toward the substrate, whereinthe temperature adjusting unit serves as the mixing unit and isconfigured to adjust the temperature of the SPM liquid by varying themixing ratio based on the temperature information of the SPM liquidacquired by the acquisition unit.
 4. The substrate processing apparatusof claim 1, wherein the acquisition unit is configured to acquire thetemperature information when the SPM liquid is supplied to a singlesheet of substrate, and the control unit controls the adjustment amountof the temperature adjusting unit when the SPM liquid is supplied to thesingle sheet of substrate.
 5. The substrate processing apparatus ofclaim 1, wherein the processing liquid supply mechanism comprises: astoring unit configured to store the sulfuric acid therein; acirculation path configured to circulate the sulfuric acid of thestoring unit therethrough; a branch path, branched off from thecirculation path, through which the sulfuric acid is flown; a mixingunit configured to generate the SPM liquid by mixing the sulfuric acidflowing in the branch path with the hydrogen peroxide at a preset mixingratio; and a discharging unit configured to discharge the SPM liquidgenerated by the mixing unit toward the substrate, wherein thetemperature adjusting unit adjusts a temperature of the sulfuric acidflowing in the circulation path.
 6. The substrate processing apparatusof claim 1, wherein the acquisition unit is implemented by a temperaturesensor configured to measure a temperature distribution of the SPMliquid on the substrate, and the control unit calculates a differencevalue between a required temperature of the SPM liquid and thetemperature of the SPM liquid on the substrate based on a temperaturedistribution characteristic obtained from the acquired temperatureinformation, and sets the adjustment amount of the temperature adjustingunit based on the calculated difference value.
 7. The substrateprocessing apparatus of claim 6, wherein the control unit sets theadjustment amount of the temperature adjusting unit based on adifference between the required temperature of the SPM liquid and atemperature value of the SPM liquid at a central zone of the substrate.8. The substrate processing apparatus of claim 6, wherein the controlunit sets the adjustment amount of the temperature adjusting unit basedon a difference between the required temperature of the SPM liquid and atemperature value of the SPM liquid at a peripheral zone of thesubstrate.
 9. The substrate processing apparatus of claim 6, wherein thecontrol unit sets the adjustment amount of the temperature adjustingunit based on a difference between the required temperature of the SPMliquid and an average value of temperature values of the SPM liquid onan entire surface of the substrate.
 10. The substrate processingapparatus of claim 6, wherein the control unit sets the adjustmentamount of the temperature adjusting unit based on a difference betweenthe required temperature of the SPM liquid and a lowest value amongtemperature values of the SPM liquid on an entire surface of thesubstrate.
 11. A processing liquid supply method of generating a SPMliquid by mixing sulfuric acid and hydrogen peroxide and supplying thegenerated SPM liquid to a substrate, the processing liquid supply methodcomprising: acquiring temperature information of the SPM liquid on asurface of the substrate; setting, based on the temperature informationacquired in the acquiring of the temperature information, an adjustmentamount of a temperature of the SPM liquid at a time when the SPM liquidis supplied to the substrate; and adjusting the temperature of the SPMliquid at the time when the SPM liquid is supplied to the substrate,based on the adjustment amount set in the setting of the adjustmentamount.